How Earth Made Us (2010) s01e03 Episode Script
Wind
NARRATOR: Our planet is full of astonishing natural wonders.
Look at that! Oh! It has immense power.
And yet, that's rarely mentioned in our history books.
I'm here to change that.
I'm looking at four ways that the power of the planet has shaped our history.
The power of fire, the source of great technological breakthroughs.
Water Oh, my gosh! You're getting all wet there.
our struggle to control it has directed human progress.
The deep Earth Blooming heck! That really is deep.
that provided the raw materials for our conquest of the planet.
But this time I'm looking at the power of the wind.
For thousands of years, the wind has shaped the destiny of peoples across the globe.
It has built fortunes and brought ruin.
Even today, we're still at the mercy of the wind.
(WIND WHISTLES) People have exploited the wind for thousands of years, on land and, most of all, at sea.
And to really experience its awesome force, this boat is the place to be.
This is one of the fastest sailing boats ever built.
It's capable of up to 5O miles an hour.
And when you're down close to the water, you can really feel that phenomenal speed.
But what makes this thing really special is when it starts to fly.
Whoo! (LAUGHS) But the real key to this craft's phenomenal breakneck pace is up there.
The sail.
There's enough of it to actually cover a tennis court, every inch of it grabbing every bit of energy from the wind and converting it to pure power.
This is the power of the wind, the atmosphere in motion, one of the most powerful and least understood forces on Earth.
We tend to think of the wind as chaotic and difficult to predict.
But when you look on a much bigger scale, at the global picture over time, a very different view emerges.
Weather systems, and with them the winds, follow the same routes around the planet again and again.
The discovery of these patterns, and sometimes the failure to understand them, lie at the heart of some of the greatest adventures in human history.
To see a remarkable example of how powerful the wind can be in changing people's lives, I've come to a small town in the middle of the Sahara Desert called Chinguetti.
Today, it's almost lost in a sea of shifting sand dunes, but once it was so much more.
There's a timelessness about this.
Some of the buildings are over 7OO years old.
There's only a few thousand people live here now, but in its heyday, this place heaved with 2O,OOO people.
And twice as many camels! Hidden away down the back streets of this crumbling town, there's a reminder of Chinguetti's glorious past.
- Bonjour.
- Ah, bonjour.
- Ca va tres bien? - Ca va, ca va.
The Al Ahmad Mahmoud Library has been run by the same family for over 3oo years and contains hundreds of ancient manuscripts.
What is the oldest? Plus ancien livre? Ah.
Le plus ancien livre chez moi - (LAUGHS) It's in a shoebox! - Ah.
It's not hermetically sealed.
- (SPEAKS FRENCH) - Oh, wow.
Look at that.
Ah.
What is this? Ca, c'est le plus vieux Coran en Afrique de l'Ouest.
It's the oldest Koran in West Africa? Dixieme siecle.
It dates back to the 1 Oth century.
Oh, look, the writing's tiny.
This priceless book is one of thousands stored in dozens of libraries throughout Chinguetti.
Ca, c'est les arabesques.
Arabesque, yeah, yeah.
The colour is beautiful.
Chinguetti's glory days were over 5oo years ago, and it owed its existence as a thriving town to the wind.
Chinguetti is in the heart of the Sahara.
It's a barren, inhospitable wilderness.
The largest desert on the planet.
Ah.
Look at that.
It just goes on and on.
The Sahara is so hostile that crossing it is dangerous and difficult.
Searing heat, no water, immense distances.
It's effectively a climate barrier.
(WIND HOWLING) Well, there's another reason why deserts and dunes are so hard to cross, and that is, they simply don't stand still.
They are constantly on the move.
In fact, these are some of the most dynamic and rapidly changing landscapes on Earth.
(COUGHS) There are few reliable landmarks, so following a route across the desert is incredibly hard.
But it's not only the shifting sand that's controlled by the wind.
The entire Sahara Desert itself was created by large-scale wind movements.
These winds begin at the equator.
This is where the sun is at its hottest, so the air is continually rising.
As it spreads away from the equator, it cools, until between about 2o and 3o degrees latitude, the air sinks back to Earth, heating up again in the process.
This pattern of winds creates a band of hot, dry deserts around the world on either side of the equator, including the Sahara and Arabian deserts.
In an era when travelling was done by foot, the desert was a formidable barrier.
For most of human history, different corners of the world have evolved as if in parallel universes, hemmed in not just by mountains and oceans, but by the desert that made climate a barrier too.
But about 1,ooo years ago, nomads were forging routes through the Sahara.
Chinguetti was an oasis town along one of these routes.
To the south was gold and ivory.
To the north, the markets of Europe.
Chinguetti's fortune was made because it was a gateway connecting two worlds that were separated by the power of the wind.
But this city's great days didn't last.
The winds that created the desert barrier had brought it riches.
But ironically, its decline was also due to the wind.
In one short period, about 5oo years ago, the world was entirely remade, transforming the fate of people around the globe.
And it was all down to a pivotal discovery about how the winds work.
This is the Gold Coast in Ghana, on the west coast of Africa.
Today, it's dominated by bustling fishing ports.
Everyone's got piles of fish! But in the 1 5th century, it was an important centre for the gold trade.
Europeans began to trade with the rich empires of West Africa, and the Portuguese built this fort, Elmina, to protect their commercial interests.
And you could say it was here that the remaking of the world began.
You know, if you'd been looking out from this spot in 1 482, you'd have seen a Portuguese ship hove into view carrying materials to build this fort.
On board was a man who would end up inadvertently changing the destiny of this whole region.
And he did that not with swords and with cannons, but with a discovery about how the Earth's atmosphere worked.
He also happened to discover a new continent.
His name? Cristoforo Colombo.
Christopher Columbus visited these shores at an important moment in European history.
In the 1 5th century, the nations of Europe were competing to find quicker, easier routes to the riches of Asia.
Christopher Columbus was a man with a plan, because he reckoned he knew a shortcut route to the Far East.
As he'd been sailing up and down this coast, he'd been keeping a close eye on the winds.
Now, the West African coast juts out into the Atlantic, so sailors here were sometimes forced into the open ocean.
Columbus realised that out there, among the rolling waves, the winds seemed to be always blowing in the same direction - away from Africa.
Columbus reckoned he could use that wind to blow him all the way round the world.
Columbus had no way of knowing whether the wind he'd encountered along the West African coast would carry on or peter out, leaving him stranded in the middle of the ocean.
But in 1 492, he headed west into the apparently endless ocean in search of his new route to the Far East.
It's hard to appreciate today just what an epic leap into the unknown this voyage was.
It took five tough weeks, but as we all know, Columbus's hunch was right - there was a wind that blew right across the Atlantic.
The thing is, his grasp of sailing was much better than his grasp of geography.
It wasn't the Far East he'd landed in.
It was the Bahamas.
As far as Europeans were concerned, he'd discovered a new continent, and for that, his name is known throughout the world.
Yet for me, America wasn't his greatest discovery.
Columbus's real genius was his instinctive understanding of the way the winds blow across the Atlantic.
He had discovered what we now call the trade winds - winds that blow steadily in a south-westerly direction.
It was the trade winds that took him all the way from the African coast to the Bahamas.
Getting across the Atlantic was all well and good, but now Columbus had to find his way back home.
And that was going to be tricky, because if he just tried to retrace his steps east, then that would carry him straight into the wind that brought him here in the first place.
Instead, Columbus headed north, along the American coast, and here he picked up another wind that blew consistently in the opposite direction, from west to east - what's known as a westerly.
At the time, it must have seemed he was just outrageously lucky with the winds.
But luck had nothing to do with it.
To prove the point, Columbus sailed back to America three more times.
Each time, he found the same winds.
Between 2o and 3o degrees latitude, the wind blew east to west.
Between 4o and 5o degrees, it blew in the opposite direction.
You know, Columbus was wrong about the continent he'd discovered, but he was right about something far more important - how to repeatedly use the circulation of the atmosphere to cross the Atlantic Ocean and get safely home.
Today, we know that the trade winds and westerlies that Columbus exploited are part of one system, the same atmospheric circulation that creates deserts over continents.
At the surface, the descending air flows back towards the equator.
These are the trade winds.
They close the loop and form what's known as an atmospheric cell.
It's the spin of the Earth that deflects these surface winds so that they move towards the Americas.
Each hemisphere has three giant atmospheric cells which define the prevailing surface winds around the entire Earth.
Once people knew about the prevailing wind patterns, it spurred them on to set sail for other new lands.
The fate of nations now depended on where they lay in relation to the winds.
The Dutch connected with the westerlies in the Southern Hemisphere to reach the Far East and ended up in control of the Dutch East Indies, or Indonesia, as it's now known.
The trade winds took them home.
In the Atlantic, Columbus's voyage formed the basis for a triangular trade route, connecting Europe, Africa and the Americas for the first time.
The Spanish crossed the Pacific using the easterly trade winds, so their ships made landfall at the Philippines, which became a Spanish colony.
To get home, the Spanish picked up the westerlies, bypassing Japan, which preserved its isolation, and landed in California.
Now, you can still see the legacy of that distant Spanish influence in the names that are so familiar to us today.
San Diego, Los Angeles and San Francisco.
Within 1 5o years of Columbus's voyage, a network of trade routes had spread out across the world.
It was the start of globalisation.
For Europeans, the conquest of the winds and waves was a triumph.
But there was a terrible price.
Many other civilisations were devastated by European contact.
Perhaps the biggest impact was here, back in Ghana.
And you can trace those changing fortunes in the story of the Elmina fort.
By the early 1 5OOs, the function of this trading fort had changed dramatically.
Gone was the bartering for ivory and gold, and instead the storerooms here were swollen with a very different kind of commodity.
These dark cellars had once contained the stock for the gold trade.
Now the fort of Elmina had become a staging post for the slave trade.
You know, it's really ugly to think of this place as a storeroom for gold and ivory and all these beautiful riches and then, just within a few years, changed into a prison.
While Europe boomed, Africa's place in the world had been changed for ever.
It looks like a way out, and in a perverse kind of way, it was.
Because after spending a couple of months locked up in the cells, you'd be taken down this long, low passageway to this - a gate barely one person wide.
This was the door of no return, because when you left here, blinking into that sharp African light, probably completely unaware of what your fate was, you'd go onto a gangplank and you'd be shipped to the Americas as slaves.
In the 4oo years after Columbus made his epic voyage, nearly 1 2 million slaves were shipped across the Atlantic.
The impact of new ocean trade routes even reached as far as Chinguetti, in the Sahara.
Sailing ships now bypassed the old desert trade routes, so the town was eclipsed by human exploitation of the very winds that had made it great.
The atmospheric cells are the framework for winds around the planet.
But there's another global wind that influences the climate, and with it, the course of human history.
High in the atmosphere are giant conductors that orchestrate weather patterns around the world.
They're called jet streams.
Jet streams are powerful currents of fast-moving wind that whip along the boundary between two cells.
They're several hundred kilometres wide but only a few kilometres thick.
They snake around the globe in wavy loops, directing the course of weather systems below.
We're only really aware of their significance when they stray from their normal path.
If the jet stream strays southward, it can send deadly tornadoes across Florida, far from their usual route to the north.
In 1 998, a jet stream wandered off course and sent a devastating ice storm across north-eastern America, leaving 45 people dead and forcing hundreds of thousands from their homes.
But perhaps the most catastrophic example of the power of the jet stream was on the High Plains of the United States in the 1 93os.
Today, towns like Capa in South Dakota lie empty and abandoned.
But in the early part of the century, farmers were rushing here to claim new land.
Then, in the 1 93os, disaster struck.
Powerful winds, intense drought and dense, choking dust storms.
It became known as the Dust Bowl.
Millions of acres of farmland turned to wasteland.
Half a million people were uprooted from their homes.
Most never returned.
At the time, it seemed like a freak accident, but we now know that the jet stream was the trigger.
For several years, it had drifted hundreds of kilometres south from its normal course, taking the rains with it.
The jet stream controls the short-term patterns of wind and weather across the world.
But perhaps the most significant way that the wind has affected history is by defining the climate and character of entire continents over thousands of years, imposing limitations for people in some parts of the world, and for others, offering huge opportunities.
Take China.
Today, China has become a world superpower.
But China's civilisation is one of the oldest in the world, and its success was built on something delivered by the wind.
This is central China.
It's known as the cradle of Chinese civilisation, because this is where the wealth and power of China's ancient dynasties began.
High above the Yellow River is what made it all possible.
A resource that was the key to China's earliest beginnings.
This plateau was the foundation stone for China's ancient agriculture.
But what made it that wasn't a stone at all.
It's what's under my feet.
It's soft and crumbly.
When you crunch it, it just turns to dust, which is exactly what it is, except it's called loess.
This dust is rich in minerals and combines with rotten plant matter to form a light, fertile soil.
Chinese farmers settled here more than 1 o,ooo years ago, and it was the first sites of rice cultivation in the world.
And the reason all this loess is here is because of the winds.
5o million years ago, India collided with Asia, and that pushed up the Himalayas.
These mountains created a completely new pattern of winds.
The Himalayas are so high that air is forced up, forming clouds and rain.
But when the wind reaches the far side of the Himalayas, it's bone dry.
It's called a rain shadow, and it forms some of the driest and dustiest places on Earth - the Taklamakan and the Gobi deserts.
So China is surrounded by giant reserves of dust, and the prevailing winds act like a huge conveyor belt that blows it all the way to central China.
Because the plateau is so vast, farming could develop here on an enormous scale.
That meant surplus food, and surplus food is the first and most important prerequisite for any self-respecting empire.
Over 3,ooo years ago, the first of China's famous dynastic empires was formed.
It was based in the centre of the loess plateau.
The Great Wall of China was built across the northern edge of the plateau to safeguard the empire's heartland.
The importance of the loess plateau has also shaped China's cultural heritage.
In the 5th century, they built these - the Buddhist temples at Yungang.
Carved into solid rock beneath the layer of loess is a honeycomb of 25o man-made caves, the walls covered with over 5o,ooo Buddhist statues.
But the crowning glory of the loess plateau is this.
The 8,ooo-strong Terracotta Army.
Not only are they buried in the loess, the terracotta from which they were created is itself made from loess.
So what began with loess led to empires and dynasties, art and religion, and it was all made possible by the winds.
China was lucky.
It found itself at the end of a wind pattern that delivered some of the finest-quality soil in the world.
Not everywhere was so fortunate.
Perhaps no continent on Earth has been more limited by the wind than Australia.
Nothing quite prepares you for the sheer scale of the Australian outback.
It's very, very barren.
I wouldn't like to be a farmer out here.
It's also amazingly dusty.
I can feel it.
Bitter taste in my mouth.
Australia's Red Centre couldn't be a harsher place to live.
If it wasn't for the odd shrub, it could be mistaken for the surface of Mars.
But at this watering hole there are signs that people settled here a very long time ago.
Carvings up to 3o,ooo years old.
And well-crafted stone tools as well.
Flat, round stones like these were used for grinding up millet seeds and tubers.
It's a very similar technology as that used by the first farmers in Asia and the Middle East.
You know, it's fascinating to think why this didn't lead to the type of farming that emerged elsewhere.
About 1 o,ooo years ago, the development of agriculture on other continents led to complex, large-scale societies.
But here, farming never really took off.
You might think that's because it's parched and dry.
But it's just as much to do with the wind.
Here you can see the effects of the wind down at ground level.
Now, what you'd normally expect to find is a kind of mixture of sand, gravel and clay, all jumbled up with plant debris to give us soil.
Instead, here you get something that looks rather bizarre.
You can see a kind of mosaic of larger fragments, where the finer stuff's just been blown away by the wind.
And what it produces is an armoured cap to the land surf
Look at that! Oh! It has immense power.
And yet, that's rarely mentioned in our history books.
I'm here to change that.
I'm looking at four ways that the power of the planet has shaped our history.
The power of fire, the source of great technological breakthroughs.
Water Oh, my gosh! You're getting all wet there.
our struggle to control it has directed human progress.
The deep Earth Blooming heck! That really is deep.
that provided the raw materials for our conquest of the planet.
But this time I'm looking at the power of the wind.
For thousands of years, the wind has shaped the destiny of peoples across the globe.
It has built fortunes and brought ruin.
Even today, we're still at the mercy of the wind.
(WIND WHISTLES) People have exploited the wind for thousands of years, on land and, most of all, at sea.
And to really experience its awesome force, this boat is the place to be.
This is one of the fastest sailing boats ever built.
It's capable of up to 5O miles an hour.
And when you're down close to the water, you can really feel that phenomenal speed.
But what makes this thing really special is when it starts to fly.
Whoo! (LAUGHS) But the real key to this craft's phenomenal breakneck pace is up there.
The sail.
There's enough of it to actually cover a tennis court, every inch of it grabbing every bit of energy from the wind and converting it to pure power.
This is the power of the wind, the atmosphere in motion, one of the most powerful and least understood forces on Earth.
We tend to think of the wind as chaotic and difficult to predict.
But when you look on a much bigger scale, at the global picture over time, a very different view emerges.
Weather systems, and with them the winds, follow the same routes around the planet again and again.
The discovery of these patterns, and sometimes the failure to understand them, lie at the heart of some of the greatest adventures in human history.
To see a remarkable example of how powerful the wind can be in changing people's lives, I've come to a small town in the middle of the Sahara Desert called Chinguetti.
Today, it's almost lost in a sea of shifting sand dunes, but once it was so much more.
There's a timelessness about this.
Some of the buildings are over 7OO years old.
There's only a few thousand people live here now, but in its heyday, this place heaved with 2O,OOO people.
And twice as many camels! Hidden away down the back streets of this crumbling town, there's a reminder of Chinguetti's glorious past.
- Bonjour.
- Ah, bonjour.
- Ca va tres bien? - Ca va, ca va.
The Al Ahmad Mahmoud Library has been run by the same family for over 3oo years and contains hundreds of ancient manuscripts.
What is the oldest? Plus ancien livre? Ah.
Le plus ancien livre chez moi - (LAUGHS) It's in a shoebox! - Ah.
It's not hermetically sealed.
- (SPEAKS FRENCH) - Oh, wow.
Look at that.
Ah.
What is this? Ca, c'est le plus vieux Coran en Afrique de l'Ouest.
It's the oldest Koran in West Africa? Dixieme siecle.
It dates back to the 1 Oth century.
Oh, look, the writing's tiny.
This priceless book is one of thousands stored in dozens of libraries throughout Chinguetti.
Ca, c'est les arabesques.
Arabesque, yeah, yeah.
The colour is beautiful.
Chinguetti's glory days were over 5oo years ago, and it owed its existence as a thriving town to the wind.
Chinguetti is in the heart of the Sahara.
It's a barren, inhospitable wilderness.
The largest desert on the planet.
Ah.
Look at that.
It just goes on and on.
The Sahara is so hostile that crossing it is dangerous and difficult.
Searing heat, no water, immense distances.
It's effectively a climate barrier.
(WIND HOWLING) Well, there's another reason why deserts and dunes are so hard to cross, and that is, they simply don't stand still.
They are constantly on the move.
In fact, these are some of the most dynamic and rapidly changing landscapes on Earth.
(COUGHS) There are few reliable landmarks, so following a route across the desert is incredibly hard.
But it's not only the shifting sand that's controlled by the wind.
The entire Sahara Desert itself was created by large-scale wind movements.
These winds begin at the equator.
This is where the sun is at its hottest, so the air is continually rising.
As it spreads away from the equator, it cools, until between about 2o and 3o degrees latitude, the air sinks back to Earth, heating up again in the process.
This pattern of winds creates a band of hot, dry deserts around the world on either side of the equator, including the Sahara and Arabian deserts.
In an era when travelling was done by foot, the desert was a formidable barrier.
For most of human history, different corners of the world have evolved as if in parallel universes, hemmed in not just by mountains and oceans, but by the desert that made climate a barrier too.
But about 1,ooo years ago, nomads were forging routes through the Sahara.
Chinguetti was an oasis town along one of these routes.
To the south was gold and ivory.
To the north, the markets of Europe.
Chinguetti's fortune was made because it was a gateway connecting two worlds that were separated by the power of the wind.
But this city's great days didn't last.
The winds that created the desert barrier had brought it riches.
But ironically, its decline was also due to the wind.
In one short period, about 5oo years ago, the world was entirely remade, transforming the fate of people around the globe.
And it was all down to a pivotal discovery about how the winds work.
This is the Gold Coast in Ghana, on the west coast of Africa.
Today, it's dominated by bustling fishing ports.
Everyone's got piles of fish! But in the 1 5th century, it was an important centre for the gold trade.
Europeans began to trade with the rich empires of West Africa, and the Portuguese built this fort, Elmina, to protect their commercial interests.
And you could say it was here that the remaking of the world began.
You know, if you'd been looking out from this spot in 1 482, you'd have seen a Portuguese ship hove into view carrying materials to build this fort.
On board was a man who would end up inadvertently changing the destiny of this whole region.
And he did that not with swords and with cannons, but with a discovery about how the Earth's atmosphere worked.
He also happened to discover a new continent.
His name? Cristoforo Colombo.
Christopher Columbus visited these shores at an important moment in European history.
In the 1 5th century, the nations of Europe were competing to find quicker, easier routes to the riches of Asia.
Christopher Columbus was a man with a plan, because he reckoned he knew a shortcut route to the Far East.
As he'd been sailing up and down this coast, he'd been keeping a close eye on the winds.
Now, the West African coast juts out into the Atlantic, so sailors here were sometimes forced into the open ocean.
Columbus realised that out there, among the rolling waves, the winds seemed to be always blowing in the same direction - away from Africa.
Columbus reckoned he could use that wind to blow him all the way round the world.
Columbus had no way of knowing whether the wind he'd encountered along the West African coast would carry on or peter out, leaving him stranded in the middle of the ocean.
But in 1 492, he headed west into the apparently endless ocean in search of his new route to the Far East.
It's hard to appreciate today just what an epic leap into the unknown this voyage was.
It took five tough weeks, but as we all know, Columbus's hunch was right - there was a wind that blew right across the Atlantic.
The thing is, his grasp of sailing was much better than his grasp of geography.
It wasn't the Far East he'd landed in.
It was the Bahamas.
As far as Europeans were concerned, he'd discovered a new continent, and for that, his name is known throughout the world.
Yet for me, America wasn't his greatest discovery.
Columbus's real genius was his instinctive understanding of the way the winds blow across the Atlantic.
He had discovered what we now call the trade winds - winds that blow steadily in a south-westerly direction.
It was the trade winds that took him all the way from the African coast to the Bahamas.
Getting across the Atlantic was all well and good, but now Columbus had to find his way back home.
And that was going to be tricky, because if he just tried to retrace his steps east, then that would carry him straight into the wind that brought him here in the first place.
Instead, Columbus headed north, along the American coast, and here he picked up another wind that blew consistently in the opposite direction, from west to east - what's known as a westerly.
At the time, it must have seemed he was just outrageously lucky with the winds.
But luck had nothing to do with it.
To prove the point, Columbus sailed back to America three more times.
Each time, he found the same winds.
Between 2o and 3o degrees latitude, the wind blew east to west.
Between 4o and 5o degrees, it blew in the opposite direction.
You know, Columbus was wrong about the continent he'd discovered, but he was right about something far more important - how to repeatedly use the circulation of the atmosphere to cross the Atlantic Ocean and get safely home.
Today, we know that the trade winds and westerlies that Columbus exploited are part of one system, the same atmospheric circulation that creates deserts over continents.
At the surface, the descending air flows back towards the equator.
These are the trade winds.
They close the loop and form what's known as an atmospheric cell.
It's the spin of the Earth that deflects these surface winds so that they move towards the Americas.
Each hemisphere has three giant atmospheric cells which define the prevailing surface winds around the entire Earth.
Once people knew about the prevailing wind patterns, it spurred them on to set sail for other new lands.
The fate of nations now depended on where they lay in relation to the winds.
The Dutch connected with the westerlies in the Southern Hemisphere to reach the Far East and ended up in control of the Dutch East Indies, or Indonesia, as it's now known.
The trade winds took them home.
In the Atlantic, Columbus's voyage formed the basis for a triangular trade route, connecting Europe, Africa and the Americas for the first time.
The Spanish crossed the Pacific using the easterly trade winds, so their ships made landfall at the Philippines, which became a Spanish colony.
To get home, the Spanish picked up the westerlies, bypassing Japan, which preserved its isolation, and landed in California.
Now, you can still see the legacy of that distant Spanish influence in the names that are so familiar to us today.
San Diego, Los Angeles and San Francisco.
Within 1 5o years of Columbus's voyage, a network of trade routes had spread out across the world.
It was the start of globalisation.
For Europeans, the conquest of the winds and waves was a triumph.
But there was a terrible price.
Many other civilisations were devastated by European contact.
Perhaps the biggest impact was here, back in Ghana.
And you can trace those changing fortunes in the story of the Elmina fort.
By the early 1 5OOs, the function of this trading fort had changed dramatically.
Gone was the bartering for ivory and gold, and instead the storerooms here were swollen with a very different kind of commodity.
These dark cellars had once contained the stock for the gold trade.
Now the fort of Elmina had become a staging post for the slave trade.
You know, it's really ugly to think of this place as a storeroom for gold and ivory and all these beautiful riches and then, just within a few years, changed into a prison.
While Europe boomed, Africa's place in the world had been changed for ever.
It looks like a way out, and in a perverse kind of way, it was.
Because after spending a couple of months locked up in the cells, you'd be taken down this long, low passageway to this - a gate barely one person wide.
This was the door of no return, because when you left here, blinking into that sharp African light, probably completely unaware of what your fate was, you'd go onto a gangplank and you'd be shipped to the Americas as slaves.
In the 4oo years after Columbus made his epic voyage, nearly 1 2 million slaves were shipped across the Atlantic.
The impact of new ocean trade routes even reached as far as Chinguetti, in the Sahara.
Sailing ships now bypassed the old desert trade routes, so the town was eclipsed by human exploitation of the very winds that had made it great.
The atmospheric cells are the framework for winds around the planet.
But there's another global wind that influences the climate, and with it, the course of human history.
High in the atmosphere are giant conductors that orchestrate weather patterns around the world.
They're called jet streams.
Jet streams are powerful currents of fast-moving wind that whip along the boundary between two cells.
They're several hundred kilometres wide but only a few kilometres thick.
They snake around the globe in wavy loops, directing the course of weather systems below.
We're only really aware of their significance when they stray from their normal path.
If the jet stream strays southward, it can send deadly tornadoes across Florida, far from their usual route to the north.
In 1 998, a jet stream wandered off course and sent a devastating ice storm across north-eastern America, leaving 45 people dead and forcing hundreds of thousands from their homes.
But perhaps the most catastrophic example of the power of the jet stream was on the High Plains of the United States in the 1 93os.
Today, towns like Capa in South Dakota lie empty and abandoned.
But in the early part of the century, farmers were rushing here to claim new land.
Then, in the 1 93os, disaster struck.
Powerful winds, intense drought and dense, choking dust storms.
It became known as the Dust Bowl.
Millions of acres of farmland turned to wasteland.
Half a million people were uprooted from their homes.
Most never returned.
At the time, it seemed like a freak accident, but we now know that the jet stream was the trigger.
For several years, it had drifted hundreds of kilometres south from its normal course, taking the rains with it.
The jet stream controls the short-term patterns of wind and weather across the world.
But perhaps the most significant way that the wind has affected history is by defining the climate and character of entire continents over thousands of years, imposing limitations for people in some parts of the world, and for others, offering huge opportunities.
Take China.
Today, China has become a world superpower.
But China's civilisation is one of the oldest in the world, and its success was built on something delivered by the wind.
This is central China.
It's known as the cradle of Chinese civilisation, because this is where the wealth and power of China's ancient dynasties began.
High above the Yellow River is what made it all possible.
A resource that was the key to China's earliest beginnings.
This plateau was the foundation stone for China's ancient agriculture.
But what made it that wasn't a stone at all.
It's what's under my feet.
It's soft and crumbly.
When you crunch it, it just turns to dust, which is exactly what it is, except it's called loess.
This dust is rich in minerals and combines with rotten plant matter to form a light, fertile soil.
Chinese farmers settled here more than 1 o,ooo years ago, and it was the first sites of rice cultivation in the world.
And the reason all this loess is here is because of the winds.
5o million years ago, India collided with Asia, and that pushed up the Himalayas.
These mountains created a completely new pattern of winds.
The Himalayas are so high that air is forced up, forming clouds and rain.
But when the wind reaches the far side of the Himalayas, it's bone dry.
It's called a rain shadow, and it forms some of the driest and dustiest places on Earth - the Taklamakan and the Gobi deserts.
So China is surrounded by giant reserves of dust, and the prevailing winds act like a huge conveyor belt that blows it all the way to central China.
Because the plateau is so vast, farming could develop here on an enormous scale.
That meant surplus food, and surplus food is the first and most important prerequisite for any self-respecting empire.
Over 3,ooo years ago, the first of China's famous dynastic empires was formed.
It was based in the centre of the loess plateau.
The Great Wall of China was built across the northern edge of the plateau to safeguard the empire's heartland.
The importance of the loess plateau has also shaped China's cultural heritage.
In the 5th century, they built these - the Buddhist temples at Yungang.
Carved into solid rock beneath the layer of loess is a honeycomb of 25o man-made caves, the walls covered with over 5o,ooo Buddhist statues.
But the crowning glory of the loess plateau is this.
The 8,ooo-strong Terracotta Army.
Not only are they buried in the loess, the terracotta from which they were created is itself made from loess.
So what began with loess led to empires and dynasties, art and religion, and it was all made possible by the winds.
China was lucky.
It found itself at the end of a wind pattern that delivered some of the finest-quality soil in the world.
Not everywhere was so fortunate.
Perhaps no continent on Earth has been more limited by the wind than Australia.
Nothing quite prepares you for the sheer scale of the Australian outback.
It's very, very barren.
I wouldn't like to be a farmer out here.
It's also amazingly dusty.
I can feel it.
Bitter taste in my mouth.
Australia's Red Centre couldn't be a harsher place to live.
If it wasn't for the odd shrub, it could be mistaken for the surface of Mars.
But at this watering hole there are signs that people settled here a very long time ago.
Carvings up to 3o,ooo years old.
And well-crafted stone tools as well.
Flat, round stones like these were used for grinding up millet seeds and tubers.
It's a very similar technology as that used by the first farmers in Asia and the Middle East.
You know, it's fascinating to think why this didn't lead to the type of farming that emerged elsewhere.
About 1 o,ooo years ago, the development of agriculture on other continents led to complex, large-scale societies.
But here, farming never really took off.
You might think that's because it's parched and dry.
But it's just as much to do with the wind.
Here you can see the effects of the wind down at ground level.
Now, what you'd normally expect to find is a kind of mixture of sand, gravel and clay, all jumbled up with plant debris to give us soil.
Instead, here you get something that looks rather bizarre.
You can see a kind of mosaic of larger fragments, where the finer stuff's just been blown away by the wind.
And what it produces is an armoured cap to the land surf